1. Field of the Invention
This invention relates to an optical apparatus and method of adjusting an optical apparatus for correcting defective eyesight. In particular, the invention relates to an optical apparatus comprising at least one liquid lens or flexible membrane mirror, and more particularly to a pair of spectacles constituted by or including such an apparatus.
2. Related Art
It is known to provide a liquid lens in the form of one or more transparent, circular, flexible membranes clamped about a peripheral zone to define a cavity. The cavity is filled with a transparent liquid, the pressure of which is adjustable by means of a positive displacement pump such as a syringe.
Adjustments of the pressure of fluid in the cavity cause variations in the curvature of the lens defined by the membranes and fluid, thereby giving rise to a lens of infinitely variable optical power.
U.S. Pat. No. 4,890,903 gives further details of liquid lenses, and of optical instruments such as spectacles incorporating such lenses. The entire disclosure of U.S. Pat. No. 4,890,903 is incorporated herein by reference.
The history of liquid lenses goes back several decades, yet there has not previously been a proposal for a truly practical sight-correcting device incorporating such lenses.